1. Field of the Invention
The present invention relates to an electronic instrument having a magnetic sensor, particularly to an electronic azimuth indicator including a part having magnetic susceptibility that affects a magnetic sensor, or to a various kinds of electronic instruments provided with such an electronic azimuth indicator.
2. Description of the Prior Art
As an example of such an electronic instrument that has been conventionally used, there is a wristwatch provided with an electronic azimuth indicator. Such a wristwatch with an electronic azimuth indicator has a problem that, when a magnetic sensor is arranged in the vicinity of a part that is susceptible to magnetization or a part assuming magnetism, accurate detection of a direction is difficult because such a part adversely affect the magnetic sensor.
To describe it more concretely, geomagnetism can be generally regarded as an even magnetic field. When a spherical magnetic body is arranged in such an even magnetic field, the magnetic field is distorted as shown in FIG. 14. FIG. 14 shows a state of the magnetic field in which a spherical magnetic body is arranged in an even magnetic field. As can be seen from the figure, the direction of the magnetic field is deflected to the direction of a spherical magnetic body 19 as shown by a magnetic field 9a in the vicinity of the spherical magnetic body 19. Such a phenomenon is observed when an article assuming magnetism (a magnetic body) is placed within the magnetic field.
In addition, an electronic instrument such as a wristwatch with an electronic azimuth indicator uses a magnetic body such as a battery and a capacitor, and particularly there are a lot of button batteries that use 304 stainless steel processed to have a circular shape. Although it is generally considered that such 304 stainless steel does not have magnetism, when the stainless steel elongates due to die cutting or bending, magnetism may occur in the direction of the elongation.
For example, as shown in FIG. 15, if the entire outer configuration of the circular stainless steel is processed to elongate in the circumference direction, the elongation occurs from the inside to the outside with respect to the outer configuration as shown by arrows. Magnetism is observed with the direction of the elongation as an axis.
Therefore, when it is necessary to arrange a magnetic sensor in the vicinity of a magnetic body or a button battery, there is a possibility that detection of magnetic field components is adversely affected due to the above-mentioned effects.
A prior art attempt at solving this problem is described in Japanese Patent Application Laid-open No. Hei 6-300869. In this prior art reference, a distance between various kinds of electronic parts and a magnetic sensor that is sufficient to eliminate influence of the electronic parts is studied in detail, and the position of the magnetic sensor is determined based on the study. That is, the magnetic sensor is arrange as far as possible from an electronic part that is susceptible to magnetization to make the influence of the electronic part to the magnetic sensor minimum.
[Problems to be Solved by the Invention]
However, the invention described in the Japanese Patent Application Laid-open No. Hei 6-300869 has a problem that, since a magnetic sensor is arranged apart from an electronic part that is susceptible to magnetization, the configuration of the magnetic sensor is considerably limited regarding a place where it is arranged, which is a substantial restriction in designing the product. Particularly, since there is a strong need for miniaturization of a portable electronic apparatus, this restriction in arrangement is a large problem from the viewpoint of securing freedom of designing including planning. Such a restriction in arrangement not only poses a problem of not being capable of adopting a novel form conforming to a fashion as an outward design (form), but also is a problem in an aspect of functionality.
That is, a size and form are a part of important functions in itself in a portable electronic instrument. For example, in the case of a portable electronic instrument, particularly a wristwatch, or a barometer, a pressure gauge and the like that are used in skydiving, skin diving or the like, a shape with a part carelessly protruding from the outer configuration or a too large shape is not only inconvenient for handling, but also is an obstacle in an emergency operation, which even has a possibility of resulting in an unexpected accident.
Further, since it is necessary to secure a distance between a part that is susceptible to magnetization and a magnetic sensor, a frame and a substrate that support the part and the sensor inevitably take a large shape. Thus, there is a problem that materials used in the frame, the substrate and the like increase in volume, which not only increases manufacturing costs but also increases packaging costs and transportation costs.
Therefore, it is an object of the present invention to provide an electronic instrument that uses a magnetic sensor and a circular or substantially circular component assuming magnetism, wherein it is not necessary to arrange the magnetic sensor spaced apart from the component. It is another object of the present invention to provide an electronic instrument that uses a circular or substantially circular component assuming magnetism in the vicinity of the circumference thereof and a magnetic sensor during processing steps of making materials and parts circular or substantially circular shape, wherein it is not necessary to arrange the magnetic sensor spaced apart from the component.
In order to attain the above-mentioned objects, a first aspect of the present invention is an electronic instrument characterized by comprising: a circular or substantially circular component that is susceptible to magnetization; a magnetic sensor to output a signal corresponding to a direction of a magnetic field that is arranged in an arbitrary position in a distance within the area of approximately 2xe2x88x921/2 of the radius from the center of the circular or substantially circular component; and correcting circuit to correct the signal outputted from the magnetic sensor in accordance with the relative position between the component and the magnetic sensor.
With this configuration, even if the magnetic sensor is located in the upper or lower side of the circular or substantially circular component that is susceptible to magnetization, since the magnetic sensor can be arranged in an arbitrary position as long as it is within a predetermined distance from the center of the component, freedom of selecting a place where the magnetic sensor is arranged is expanded in designing the electronic instrument, and miniaturization and the like of an electronic instrument can be attained while maintaining high precision.
An electronic instrument in accordance with a second aspect of the present invention is an electronic instrument having a magnetic sensor, characterized by comprising: a circular or substantially circular component that is susceptible to magnetization; a magnetic sensor to output a signal corresponding to a direction of a magnetic field that is arranged in an arbitrary position on a straight line passing the center of the component such that the straight line and a detection axis of the magnetism coincide; and correcting circuit to correct the signal outputted from the magnetic sensor in accordance with the relative position between the component and the magnetic sensor.
With this configuration, even if the magnetic sensor cannot be arranged in an arbitrary position within a predetermined distance from the center of the circular or substantially circular component that is susceptible to magnetization, since it is possible to arrange the magnetic sensor in an arbitrary position on a straight line passing the center of the component such that the straight line and a detection axis of the magnetism coincide, freedom of selecting a place where the magnetic sensor is arranged is expanded in designing the electronic instrument, and miniaturization and the like of an electronic instrument can be attained while maintaining high precision.
An electronic instrument in accordance with the third aspect of the present invention is an electronic instrument having a magnetic sensor, characterized by comprising: a circular or substantially circular component that is susceptible to magnetization; an X axis magnetic sensor for detecting a magnetic field component in an X axis direction that is arranged in an arbitrary position in a distance within the area of approximately 2xe2x88x921/2 of the radius from the center of the component, or is arranged such that a detection axis of the magnetic sensor overlaps an X axis passing through the center of the component in an arbitrary position on the X axis or on its extended line; a Y axis magnetic sensor for detecting a magnetic field component in a Y axis direction that is arranged in an arbitrary position in a distance within the area of approximately 2xe2x88x92xc2xd of the radius from the center of the component, or is arranged such that a detection axis of the magnetic sensor overlaps a Y axis passing through the center of the component and perpendicular to the X axis in an arbitrary position on the Y axis or on its extended line; and correcting circuit to correct the signals outputted from the X axis magnetic sensor and the Y axis magnetic sensor in accordance with the relative position between the component and the X and Y magnetic axes.
With this configuration, since each of the X axis magnetic sensor and the Y axis magnetic sensor can be arranged in an arbitrary position within a predetermined distance from the center of the circular or substantially circular component, or in an arbitrary position on a straight line passing the center of the component where the arbitrary line and a detection axis of the magnetism coincide, freedom of designing can be further increased, and miniaturization and the like of an electronic instrument can be attained while maintaining high precision.
An electronic instrument in accordance with a fourth aspect of the present invention is an electronic instrument having a magnetic sensor characterized in that the component that is susceptible to magnetization is a battery made of 304 stainless steel. Recently, there are many electronic parts such as a button battery that have the size of the above-mentioned battery, which in conjunction with this configuration, makes it possible to make an electronic instrument using such a battery higher in performance, miniaturized, and so forth.
An electronic instrument in accordance with a fifth aspect of the present invention is an electronic instrument having a magnetic sensor, characterized by comprising: a circular or substantially circular component assuming magnetism in the vicinity of its circumference by processing; a magnetic sensor to output a signal corresponding to a direction of a magnetic field that is arranged in a position inside the vicinity of the circumference assuming magnetism of the circular or substantially circular component; and correcting circuit to correct the signal outputted by the magnetic sensor in accordance with the relative position between the component and the magnetic sensor.
With this configuration, even if the magnetic sensor is arranged in the upper and the lower side of the circular or substantially circular component assuming magnetism in the vicinity of its circumference by processing, since the magnetic sensor can be arranged in an arbitrary position as long as it is within a predetermined distance from the center of the component, freedom of selecting a place where the magnetic sensor is arranged is expanded in designing the electronic instrument, and miniaturization and the like of an electronic instrument can be attained while maintaining high precision.
An electronic instrument in accordance with a sixth aspect of the present invention is an electronic instrument having a magnetic sensor, characterized by comprising: a circular or substantially circular component assuming magnetism in the vicinity of its circumference by processing; a magnetic sensor to output a signal corresponding to a direction of a magnetic field that is arranged in an arbitrary position on a straight line passing the center of the component such that the straight line and a detection axis of magnetism coincide; and correcting circuit to correct the signal outputted from the magnetic sensor depending on the relative position between the component and the magnetic sensor.
With this configuration, even if the magnetic sensor cannot be arranged in an arbitrary position within a predetermined distance from the center of the circular or substantially circular component assuming magnetism in the vicinity of its circumference by processing, since the magnetic sensor can be arranged in an arbitrary position on an arbitrary straight line passing through the center of the component such that the straight line and an detection axis of magnetism coincide, freedom of selecting a place where the magnetic sensor is arranged is expanded in designing the electronic instrument, and miniaturization and the like of an electronic instrument can be attained while maintaining high precision.
An electronic instrument in accordance with a seventh aspect of the present invention is an electronic instrument having a magnetic sensor, characterized by comprising: a circular or substantially circular component assuming magnetism in the vicinity of its circumference by processing; an X axis magnetic sensor for detecting a magnetic field component in an X axis direction that is arranged in a position inside the vicinity of the circumference assuming magnetism of the circular or substantially circular component, or is positioned such that a detection axis of the magnetic sensor overlaps an X axis passing the center of the component in an arbitrary position on the X axis or on its extended line; a Y axis magnetic sensor for detecting a magnetic component in a Y axis direction that is arranged inside the vicinity of the circumference assuming magnetism of the circular or substantially circular component, or is arranged such that a detection axis of the magnetic sensor overlaps a Y axis passing the center of the component and perpendicular to the X axis in an arbitrary position on the Y axis or on its extended line; and correcting circuit to correct the signals outputted from the X axis magnetic sensor and the Y axis magnetic sensor in accordance with the relative position between the magnetic sensor and the X axis and the Y axis magnetic sensors.
With this configuration, since each of the X axis magnetic sensor and the Y axis magnetic sensor can be arranged in an arbitrary position within a predetermined distance from the center of the circular or substantially circular component assuming magnetism in the vicinity of its circumference by processing or in an arbitrary position on an arbitrary straight line passing the center of the component such that the straight line and an detection axis of magnetism coincide, freedom of designing can be further increased, and miniaturization of an electronic instrument can be attained while maintaining high precision.
An electronic instrument in accordance with an eighth aspect of the present invention is an electronic instrument having a magnetic sensor characterized in that the circular or substantially circular component assuming magnetism in the vicinity of its circumference by processing is a battery made of 304 stainless steel.
With this configuration, in conjunction with existing many electronic parts such as a button battery that have the size of the above-mentioned battery, an electronic instrument using such an electronic part can be made higher in performance, further miniaturized, and so forth.
An electronic instrument in accordance with a ninth aspect of the present invention is an electronic instrument having a magnetic sensor, characterized in that the magnetic sensor, the Y axis magnetic sensor or the X axis magnetic sensor consists of a two axis magnetic sensor that is capable of measuring both the magnetic field components in the X axis direction and in the Y axis direction perpendicular to the X axis.
With this configuration, since the two axes can be measured by one magnetic sensor, an electronic instrument can be made higher in performance, more miniaturized, and so forth.
An electronic instrument in accordance with a tenth aspect of the present invention is characterized in that the electronic instrument is an electronic azimuth indicator, a wristwatch with an electronic azimuth indicator, a pressure gauge with an electronic azimuth indicator, a car navigation terminal apparatus, a portable electronic instrument with an electronic azimuth indicator, or an electronic instrument with an electronic azimuth indicator.
With this configuration, freedom of designing many electronic instruments such as the above-mentioned ones having magnetic sensors can be increased, and miniaturization and higher performance of the electronic instruments are made possible.